@amcharts/amcharts5
Version:
amCharts 5
109 lines • 4.24 kB
JavaScript
import { SimpleLineSeries } from "./SimpleLineSeries";
function round(number, precision) {
const factor = Math.pow(10, precision);
return Math.round(number * factor) / factor;
}
// Modified from the regression npm package (under the MIT license)
function linear(data, precision = 2) {
const sum = [0, 0, 0, 0, 0];
let len = 0;
for (let n = 0; n < data.length; n++) {
if (data[n][1] !== null) {
len++;
sum[0] += data[n][0];
sum[1] += data[n][1];
sum[2] += data[n][0] * data[n][0];
sum[3] += data[n][0] * data[n][1];
sum[4] += data[n][1] * data[n][1];
}
}
const run = ((len * sum[2]) - (sum[0] * sum[0]));
const rise = ((len * sum[3]) - (sum[0] * sum[1]));
const gradient = run === 0 ? 0 : round(rise / run, precision);
const intercept = round((sum[1] / len) - ((gradient * sum[0]) / len), precision);
function predict(x) {
return [
round(x, precision),
round((gradient * x) + intercept, precision)
];
}
return data.map(point => predict(point[0]));
}
export class RegressionSeries extends SimpleLineSeries {
constructor() {
super(...arguments);
Object.defineProperty(this, "_tag", {
enumerable: true,
configurable: true,
writable: true,
value: "regression"
});
}
_afterNew() {
super._afterNew();
this.setPrivate("allowChangeSnap", false);
this.set("snapToData", true);
}
_updateSegment(index) {
const diP1 = this._di[index]["p1"];
const diP2 = this._di[index]["p2"];
const series = this.get("series");
if (series && diP1 && diP2) {
const xAxis = series.get("xAxis");
let x1 = this._getXValue(diP1.get("valueX"));
let x2 = this._getXValue(diP2.get("valueX"));
const di1 = xAxis.getSeriesItem(series, xAxis.valueToPosition(x1));
const di2 = xAxis.getSeriesItem(series, xAxis.valueToPosition(x2));
const field = this.get("field") + "Y";
if (di1 && di2) {
const dataItems = series.dataItems;
let startIndex = dataItems.indexOf(di1);
let endIndex = dataItems.indexOf(di2);
let inversed = false;
if (startIndex > endIndex) {
inversed = true;
[startIndex, endIndex] = [endIndex, startIndex];
}
const points = [];
let ii = 0;
for (let i = startIndex; i <= endIndex; i++) {
const dataItem = dataItems[i];
points.push([ii, dataItem.get(field)]);
ii++;
}
const resultPoints = linear(points);
const len = resultPoints.length;
if (len > 1) {
const p1 = resultPoints[0];
const p2 = resultPoints[resultPoints.length - 1];
if (p1 && p2) {
let y1 = p1[1];
let y2 = p2[1];
if (inversed) {
[y1, y2] = [y2, y1];
}
this._setContext(diP1, "valueY", y1, true);
this._setContext(diP2, "valueY", y2, true);
this._setContext(diP1, "valueX", x1);
this._setContext(diP2, "valueX", x2);
this._positionBullets(diP1);
this._positionBullets(diP2);
}
}
}
}
}
}
Object.defineProperty(RegressionSeries, "className", {
enumerable: true,
configurable: true,
writable: true,
value: "RegressionSeries"
});
Object.defineProperty(RegressionSeries, "classNames", {
enumerable: true,
configurable: true,
writable: true,
value: SimpleLineSeries.classNames.concat([RegressionSeries.className])
});
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